Design Techniques Towards a Full-Rate

We investigate high-speed design techniques that enable realization of a full-rate broadband serializer operating at 40Gb/s using a 0.18µm CMOS process. Bandwidth enhancement techniques, including shunt-peaking and multi-pole band-width enhancement, have been incorporated in the di erent high speed blocks in the serializer. Different inductor structures have been studied and appropriately incorporated for bandwidth enhancement and resonating circuits, consistent with various constraints on speed, quality factor, and chip area. A novel dynamic re-timing circuit capable of clocked 40GHz operation is presented, which reduces the duty-cycle distortion at the serial output. A low-power distributed bu er with unequal characteristic impedances in the gate line and drain line is designed as a 40Gb/s output bu er. A method for generating a differential 40GHz clock using two coupled 20GHz oscillators with a "push-push" topology is also proposed. Harmonic distortion and phase noise of a 40GHz push-push VCO with appropriate buffering of the 20GHz and 40GHz clock signals are studied.